/Engine/Source/Runtime/SlateCore/Public/Layout/Geometry.h
Translates the local coordinates into local coordinates that after being transformed into absolute space will be rounded to a whole number or approximately a whole number. This is important for cases where you want to show a popup or a tooltip and not have the window start on a half pixel, which can cause the contents to jitter in relation to each other as the tooltip or popup moves around.
[UE::Slate::FDeprecateVector2DResult](API\Runtime\SlateCore\Types\FDeprecateVector2DResult) LocalToRoundedLocal ( [UE::Slate::FDeprecateVector2DParameter](API\Runtime\SlateCore\Types\FDeprecateVector2DParameter) LocalCoordinate ) const